Rare earth magnets having R-T-B (R=rare earth element, T=metal element such as Fe) systems exhibit excellent magnetic properties, and much research is being devoted to further improving their magnetic properties. The residual flux density (Br) and coercive force (HcJ) are commonly used as indicators of the magnetic properties of magnets, and a larger product of these factors (maximum energy product) is associated with magnets of superior magnetic properties.
The Br or HcJ value of a rare earth magnet is known to vary according to the composition. For example, Patent documents 1-3 disclose rare earth magnets having characteristic compositions for the purpose of improving the Br or HcJ value.    [Patent document 1] International Patent Publication No. WO 2004/029995    [Patent document 2] Japanese Unexamined Patent Publication No. 2000-234151    [Patent document 3] International Patent Publication No. WO 2005/015580